Streaming authentication using chained identifiers

ABSTRACT

An apparatus, intended for use in an authentication event, having a hardware processor, a memory, a receiver/transmitter unit, a stream block generation module adapted to enable the hardware processor to generate and store a plurality of stream blocks including at least a stream block and a first preceding stream block; a stream block streaming module adapted to enable the hardware processor to control the receiver/transmitter unit to output the stream block; and a moving window module adapted to enable the hardware processor to control the receiver/transmitter unit to output, as a stream proof, at least one of a moving window of the plurality of stream blocks in connection with an authentication event.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority from (1) U.S. Provisional Patent Application No. 62/549,259 filed Aug. 23, 2017 and also from (2) U.S. Provisional Patent Application No. 62/582,177 filed Nov. 6, 2017. This application incorporates the entirety of each of the two above-identified disclosures by this reference.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The drawings constitute part of this specification and illustrate example implementations of authentication using chained identifiers.

FIG. 1 provides a high level, simplified, schematic style overview of an example implementation.

FIG. 2 shows, in simplified schematic form, an example of any given device of any given user.

FIG. 3 depicts in a highly simplified, schematic manner, an alternative implementation of a chained identifier store and an alternative implementation of an authentication server.

FIG. 4 depicts a general sequence of actions in one algorithm that effects an authentication operation in one example implementation.

FIG. 5 depicts a general sequence of actions in another algorithm that effects an authentication operation in another example implementation.

FIG. 6 depicts a general sequence of actions in an algorithm for registration of a new account and for registration of an associated device.

FIG. 7 depicts a general sequence of actions in an algorithm for registering a new device of an existing account.

FIG. 8 depicts a general sequence of actions in an algorithm for writing a stream block to a distributed ledger system.

FIG. 9 explains, in pictorial form, an algorithm for handling communication interruptions arising while writing stream blocks to a distributed ledger system.

DETAILED DESCRIPTION

This paper discloses a system and method for authentication using streams of chained identifiers, also referred to as stream blocks, and an apparatus adapted for use in such a system. One implementation of the system includes a distributed ledger as a store for the chained identifiers and a method of distributed ledger operation. The distributed ledger in one example implementation is a blockchain. For a brief overview of blockchain technology, the reader may consult, for example, United States Published Patent Application 20170366348A1. This document's discussion of blockchain technology found in paragraphs 0030 through 0031 and their associated figures are incorporated herein by this reference.

FIG. 1 illustrates, in a high level, simplified, schematic style, a system 10 that performs authentication using stream blocks. FIG. 1 illustrates a user base 1000, a stream block 2000, a chained identifier store 3000, and an authentication server 4000.

See the column “user” depicted in FIG. 1. User base 1000 includes at least one user A and optionally includes other users such as user B, and optionally includes an arbitrarily large number of users. One of the users depicted in FIG. 1 is a generically representative user U(x). User U(x) represents any given user.

The one or more users each have one or more respective devices. See the column “device” in FIG. 1. For example, user A has two respective devices: device D1 and device D2. User B has three respective devices: device D1, device D3, and device D4. User U(x) has one or more respective devices including a generically representative device D(x). Device D(x) of user U(x) represents any given device of any given user.

In one example implementation of the user base 1000, two users share a common device such as a laptop or a terminal. In this example, the device D1 of user A is the same physical device as device D1 of user B and D1 represents a universally unique identifier of this particular device. In this instance the device, when used by one user, would be identified by one stream of chained identifier. When used by the other user the device would be identified by a different stream.

In FIG. 1, a device D(x) is a discrete machine such as a smart watch, mobile phone, tablet, workstation, voice-controlled home unit, or the like. In an alternative example, the device D(x) is a browser running on a discrete machine. In yet another alternative example, the device D(x) is a smart, connected device such as a smart thermostat, a smart household appliance, a household robot such as a floor cleaner, or the like.

Each device D(x) stores or has access to one or more applications that require authentication of the user U(x). In FIG. 1, the applications are generally depicted by lower-case letters in the column “apps” of the user base 1000. The term “apps” is not intended to be limited only to an application available from one of the popular app stores but is meant to more generally refer to any software application that involves an authentication event. In FIG. 1, user A has a respective device D1 that uses respective apps “a”, “b”, and “c”. User A has a respective device D2 that uses respective apps “a” and “b”. User B's three respective devices each use respective apps “a”, “b”, and “c”. The device D(x) of user U(x) runs a generically representative application “(x)”. App (x) of device D(x) of user U(x) represents any given application running on any given device of any given user.

See the column “stream blocks” in FIG. 1. The first row includes the following symbols in italic font: “A:D1:a:”. The symbols represent, in order, an identifier “A” that signifies user A; an identifier “D1” that signifies device D1 and, in view of its position after identifier “A”, further signifies device D1 of user A; an identifier “a” that signifies app “a” and, in view of its position after the identifiers “A:D1”, further signifies app “a” running on device D1 of user A. Similarly, the final row in the column “stream blocks” includes the following symbols: “X:Dx:x:”. These symbols signify app “x” any given application) running on device Dx (i.e., any given device) of user U(x) (i.e., any given user). These symbols in italic font may be thought of in a general sense as explanatory indicia.

These explanatory indicia are provided for the sake of this explanation only so that the reader can more easily track how the stream blocks are created, stored, communicated, and used. For the sake of the discussion below, the explanatory indicia may also be referred to as “stream identifiers”.

Each of the stream identifiers may be understood to relate, on a one-to-one basis, to a corresponding stream of stream blocks that begins with an original (or origin) stream block [000] and continues with a first stream block [001], a second stream block [002], and so on, up until a current stream block [n]. Here, the numbers in between square brackets are ordinal numbers that tell the order in which a given stream block was produced within a given stream of stream blocks.

Return to the column “stream blocks” in FIG. 1. The first row pertains to stream identifier A:D1:a:. This stream includes the symbols “[175][176][177]” representing three individual stream blocks. The stream block [177] is the one hundred seventy-seventh stream block produced for the given stream after the origin stream block [000]. In FIG. 1, the current stream block in stream identifier A:D1:a: is [177]. The first preceding stream block relative to [177] is [176]. The second preceding stream block relative to [177] is [175]. In the example shown in FIG. 1, device D1 of user A locally stores the three most recent stream blocks of stream identifier A:D1:a:. In the state shown in FIG. 1, all of the stream blocks from [000] to [177] have been previously output from device D1 of user A. The stream blocks prior to [175] have also, in one example implementation, previously been discarded by the device.

The final row pertains to stream identifier X:Dx:x:. The device D(x) of user U(x) locally stores the three most recent stream blocks of stream X:Dx:x:, namely, the current stream block [n], the first preceding stream block [n−1], and the second preceding stream block [n−2]. The number of stream blocks stored locally is configurable. Other example implementations store a number of stream blocks other than three.

The locally stored stream blocks may be thought of as a moving window into a given stream of stream blocks. For example, in the first row in the column “stream blocks”, the locally-stored stream blocks include [175], [176], and [177]. At a future time, stream block [178] will be produced and communicated outside of device D1 of user A and will also be stored as one of the locally-stored stream blocks with the result that stream block [175] will no longer be considered part of the window. The window at that future time will include [176], [177], and [178]. Since the content of the three most recent stream blocks changes with each newly-generated stream block, the view of the three most recent stream blocks is thereby a moving window into the stream.

In FIG. 1, each app is authenticated using streaming blocks. Each app secured by this streaming authentication that runs on a given device has a corresponding stream of stream blocks. Each such stream begins with an origin streamblock [000]. Each subsequent stream block that is produced extends the stream. Here, “stream” does not imply the nonstop generation and outputting of stream blocks. Instead, a “stream” is an ordered set of stream blocks for a given app running on a given device of a given user over time.

The moving window of each stream of stream blocks depicted in FIG. 1 is configured as three, namely, the current stream block, the first preceding stream block, and the second preceding streamblock. The number of stream blocks in the moving window may be alternatively expressed as w=3 where w represents the size of the moving window and 3 indicates the number of stream blocks considered to be within the window.

Although this discussion generally explains example implementations where the moving window size is w=3, this value is configurable: in other example implementations, the moving window is a size other than w=3.

A more general expression for the set m of the stream blocks of a given stream within the moving window is given by:

$m = {\overset{w - 1}{\underset{i = 0}{}}\left\lbrack {n - i} \right\rbrack}$ where the ∥ operator indicates a concatenation operation or similar and where [n−i] represents the stream block in the stream having the ordinal position of the current stream block less i. Thus, for a moving window with a window size of w=10, the set m of stream blocks in the moving window include [n][n−1][n−2] . . . [n−9]. Here, [n] is the current stream block; [n−1] is the immediate precedent of [n]; [n−2] is the immediate precedent of [n−1] and so on. The stream blocks are stored, in one implementation, in a secure local storage. The stream blocks are stored, in various implementations, in a ring data structure, a list data structure, a queue data structure, or the like.

FIG. 1 shows a more detailed view of an example of a given stream block 2000 according to one example. The stream block 2000 includes one or more fields identified as field1 2000-1, field2 2000-2, etc., up to the final field field(x) 2000-x. The fields of stream block 2000 are shown stacked one on top of the other for the sake of explanation and understandability. The fields are shown as having an identical length, but this too is only for the sake of explanation and does not imply that the actual fields need to be the same length. The fields are shown in order from 1 to x, but this does not imply any particular importance unless stated otherwise below.

In one example, the stream block 2000 may be thought of as a block of information that has a number of fields. The fields, according to this example implementation, contain (1) a version number that designates the format of the block; (2) a sequence number for the block; (3) a timestamp taken from when the block was created; (4) an identifier for the user or account; (5) an identifier for the device; (6) an identifier for the app on this device when used by the indicated user (also referred to as a number); (7) a hash of the immediately preceding block from the same stream identifier; and (8) a random number that changes with each block and adds cryptographic entropy to the block. The first through eighth fields are hashed to form another field: (9) a hash of the current block. In one implementation, the block is signed with a private key. In other implementations, the transport network that carries the block is trusted at a level that precludes the need to sign the block The fields, taken together, constitute a “streamblock” (here, the term “stream block” is used to distinguish this type of block from other blocks such as the chain block discussed later).

In the one example just described, certain fields (field4, field5, and field6) contain information that could be used to identify a particular user. In other words, such fields contain personally identifiable information (PII).

In an alternative implementation, these fields are replaced with random numbers generated as unique identifiers. The correspondence, between these random numbers generated as unique identifiers to logical user accounts, for a given app, is maintained in a location (such as customer account registry 4700 described below) that maximizes the protection of the PII of user U(x). In this alternative implementation, no PII is transmitted.

In detail, the fields, according to this alternative implementation, contain (1) a version number that designates the format of the block; (2) a sequence number for the block; (3) a timestamp taken from when the block was created; (4) a random number generated as a unique identifier for the user or account, that is, an account identifier; (5) a random number generated as a unique identifier for the device; (6) a random number generated as a unique identifier for the app on this device when used by the indicated user (also referred to as a number); (7) a hash of the immediately preceding block from the same stream identifier; and (8) a random number generated as a cryptographic ‘salt’ to increase entropy. The first through eighth fields are hashed to form another field: (9) a hash of the current block.

Here, the stream blocks contain indications of the user, a device of the user, and an app of the device. Since the indications are random numbers the indications are free of personally identifiable information.

In the one example implementation and the alternative implementation just described, each stream block is generated from a given stream identifier and is unique to the user U(x), the device D(x), and the app (x). Each stream block therefore is an identifier for the user operating the app on the device. Since each current stream block (other than origin stream blocks) contains a hash of its first preceding stream block, the stream blocks are chained. The stream is therefore a stream of chained identifiers.

Each stream block [n] after stream block [000] (also referred to as an Origin Stream Block or OStBlk) is affected by its first preceding stream block that, in turn, was previously affected by its respective first preceding stream block, and so forth. The stream of chained identifiers evolves with each new stream block, and the unpredictability of each new stream block imbues the stream with a non-deterministic but emergent quality that reflects a totality of previous affects through the entire chain. The uniqueness of each stream of stream blocks enables the use of the stream in an authentication operation.

Chained identifier store 3000 in FIG. 1 stores the chained identifiers (i.e., the stream blocks). As before, the items appearing in italic font are explanatory indicia provided so that the reader can more easily track the flow of stream blocks from device to chained identifier store 3000 and are not necessarily part of the actual data stored. In this example, the chained identifier store 3000 stores each stream block from each app (x) of each device D(x) of each user U(x) from the origin stream block [000] to the current stream block [n].

Each device D(x) in the user base 1000 produces stream blocks, and the stream blocks are communicated to and stored in the chained identifier store 3000, generally as they are produced (although communication delays can delay the storing of stream blocks as discussed below). In one example implementation, each device D(x) generates one stream block [n] on a periodic basis, such as every few seconds or minutes. The production continues without cease on this periodic basis so long as the device D(x) has power. The device D(x) attempts to communicate the stream block [n] for storage in the chained identifier store 3000 as soon as the stream block is produced. When a given device D(x) cannot communicate the current stream block for storage in the chained identifier store 3000, in one implementation the given device D(x) maintains a backlog pool of stream blocks to be transmitted once communication is restored. In another example implementation, when the capacity for storing the backlog pool on the given device D(x) is exhausted, the oldest uncommitted one or more stream blocks are deleted to make room for storing the new current stream block as discussed below in the context of FIG. 9. One concrete implementation uses a ring buffer.

In another example implementation, each device D(x) generates stream blocks on the periodic basis already mentioned, and also in response to a predetermined event such as in response to detecting device power-on, initial registration of the device on the network, or in response to an authentication event. For example, when the stream in chained identifier store 3000 is not sufficiently recent (i.e., is “stale”), the device is prompted to freshen the stream by generating and writing new stream blocks to the chained identifier store 3000.

In the foregoing example implementations, once the device D(x) has been configured or adapted in a manner described further below (see FIG. 2) the production and communication of streams of stream blocks occur without user intervention and without the need for user awareness of these activities.

The continuing, periodic or semi-periodic flow of stream blocks from all the devices of the user base 1000 to the chained identifier store 3000 is depicted in FIG. 1 by a set of bold lines emanating from the right-hand side of each of the streams A:D1:a: through X:Dx:x: and terminating in a solid, bold arrowhead that touches the left edge of chained identifier store 3000.

The chained identifier store 3000 is graphically depicted as a database. In one example, the chained identifier store 3000 is a relational database management system. In another example, the chained identifier store 3000 is implemented as a distributed relational database. In yet another example, to be described below in more detail, the chained identifier store 3000 is a distributed ledger or, in a specific implementation, is a blockchain (see FIG. 3).

The authentication server 4000 in FIG. 1 is responsible for handling an authentication event. For example, assume user U(x) attempts to use device D(x) to run app (x). Here, app (x) involves access to content or functionality that cannot be gained without authentication.

In one example implementation, authentication is performed using only the chained identifiers without the need of a username and password. In another example implementation, user U(x) is subjected to a username/password type of authentication challenge, and the chained identifiers are used as an additional authentication factor. In other example implementations, the chained identifiers are used in conjunction with any combination of one or more other authentication factors.

Referring back to FIG. 1, with the user base 1000 and chained identifier store 3000 in the state shown, user U(x) attempts to access app (x) on device D(x). The access attempt is addressed to or subsequently directed to authentication server 4000. Authentication server 4000 responds to the access attempt by issuing a streaming block authentication challenge that requests the device D(x) to respond with stream blocks in the moving window for the app (x).

As shown in FIG. 1, the device D(x) responds to the streaming block authentication challenge in this implementation by transmitting to the authentication server 4000 all of the contents of the moving window for app (x), namely, stream blocks [n], [n−1], and [n−2] (see the hollow arrow between D(x) and authentication server 4000). The contents of the moving window are depicted in FIG. 1 between curly braces. Here, the curly braces signify only that the stream blocks are suitably formatted for transmission to the authentication server 4000. For example, the contents of the moving window are serialized according to a predetermined format acceptable to the authentication server 4000 and then packetized for network communication. Further, for example, the packets are encrypted.

Since the authentication server does not store the stream blocks as they are produced, but has only the present transmitted moving window, the authentication server must issue a query to the chained identifier store 3000 to request a set of the stream blocks, of the stream X:Dx:x (i.e., the stream corresponding to the use of app (x) on device D(x) by user U(x)), previously received by chained identifier store 3000.

The chained identifier store 3000 responds to the query by providing the requested set of previously received stream blocks. The requested set of stream blocks in one example implementation includes just the same number of stream blocks as are in the moving window. In an alternative example, the requested set of stream blocks includes more stream blocks than are in the moving window so as to account for the possibility of minor communications or processing delays. The query of the authentication server 4000 and the response of the chained identifier store 3000 are depicted in FIG. 1 by hollow arrows labeled respectively as “query” and “response.”

The authentication server in this example compares each stream block received directly from the device D(x) with the corresponding stream blocks received from the chained identifier store 3000 in response to the query. This operation is depicted within authentication server 4000 by a process that receives two inputs and outputs success when the inputs match. When each stream block of the device's moving window matches a corresponding one retrieved from the chained identifier store 3000, then the user U(x) is deemed to have successfully met the streaming block authentication challenge. In this situation, the authentication server 4000 outputs an indication of success indicating proper authentication for the streaming stream blocks factor.

In an alternative implementation, the authentication server 4000 simply sends the received moving window of stream blocks to the chained identifier store 3000 together with a request to check those stream blocks against the given stream. Here, the chained identifier store 3000 makes the determination as to whether the moving window of stream blocks sufficiently corresponds to the given stream that the authentication response of the user's device should be deemed valid.

In the implementation just discussed, a streaming block authentication challenge is made to the device D(x), and the reply includes the stream proof. This reply includes stream blocks from the moving window. In another implementation, the device does not wait for a streaming block authentication challenge before sending the stream proof. Instead, on occasions where the device D(x) is in an unauthenticated state, the device sends the stream proof as part of a message requesting access.

In the implementation discussed above in FIG. 1 and also below in FIG. 4, the reply to the streaming block authentication challenge includes a stream proof of all the stream blocks of the moving window. In other implementations, the stream proof includes fewer than all of the stream blocks of the moving window. Both implementations are more generally described as the sending of stream blocks “from” or “of” the moving window (in contrast to the sending of the moving window, which implies that all of the stream blocks in the moving window are sent). In one implementation, the stream proof output by the device D(x) includes stream blocks of the moving window. In another implementation, the stream proof includes just a hash for each of the stream blocks.

Some example implementations thus include a plurality of stream blocks as the stream proof, i.e., full copies of the stream blocks. Other example implementations include as the stream proof information sufficient to show possession of the plurality of stream blocks, i.e., hashes of the stream blocks. In the latter case, the stream proof is, in a more general sense, said to include proof of possession of a plurality of stream blocks since hashes are not the only way to show proof of possession and other proofs are used in various alternative implementations.

The implementation in which hashes of stream blocks are sent as the stream proof, instead of the stream blocks themselves, improves the internal efficiency of the device D(x), the authentication server 4000, and the chained identifier store 3000 not to mention the network itself.

The internal efficiency of the device D(x) is improved in that the module that formulates the stream proof needs to send much less data. In the example of stream block 2000, only the ninth field (field 9) is sent, reducing the amount of data to be sent by at least 75%. The hash for each stream block is computed at the time the stream block is generated, so no additional hash processing is necessary, thereby avoiding the need to expend hardware processor cycles to generate the hash values to be sent. In addition, sending the hash of a stream block is sufficient to demonstrate possession of the stream block since the probability of correctly guessing a given hash value is low. Moreover, where the stream proof includes the respective hash value for more than one block, the odds against correctly guessing all hash values increases exponentially.

The authentication server 4000 also gains efficiency in this implementation of stream proof by sending only hashes. The message containing the stream proof is much shorter, and fewer cycles of the hardware processor are spent in handling the message. Similarly, the authentication server interacts with the chained identifier store 3000 by comparatively succinct communications.

The improvement to efficiency of the chained identifier store 3000 comes from a faster comparison operation. Although in one implementation the chained identifier store 3000 is equipped with machine code that enables its nodes to handle stream proofs in the form of complete stream blocks, in other implementations the nodes are enabled also by other machine code to handle stream proofs in the form of only hashes. Determining an exact match for each hash in a stream proof is less processor-intensive and less memory-intensive than determining an exact match for each stream block. The reduction in processor and memory use can be as much as 75%.

The network itself finds in the stream-proof-by-hash approach a reduced level of traffic when stream proofs are sent compared to the stream-proof-by-block approach. Some of the technical effects of authentication using streaming stream blocks are now discussed.

Authentication using streaming stream blocks as a separate factor compares favorably with authentication using a random one-time password (OTP), which is typically in the form of a numeric code, dynamically provided through SMS or email at the time of an authentication event. First, an OTP provided through SMS or the like is provided by the server to the device and is therefore generated by the server. Outputting the moving window of streaming stream blocks, on the other hand, does not require the server to generate anything. This has the technical effect of simplifying the logic that must be provided on the server and also reduces the load on the server's memory and processor.

Second, when an OTP is dynamically supplied to a user the user must view, remember, and type in the OTP. These tasks become more difficult as OTPs trend longer and devices trend smaller. The moving window of streaming stream blocks, on the other hand, does not require the user to perform any data entry: the data in the moving window are stored when created and simply supplied by the device in response to an authentication challenge.

Third, when a dynamic, random OTP is offered to users as an authentication factor, the offer is typically optional. In order to avoid driving consumers to less-burdensome online platforms that do not require extra steps at login, enterprises typically give users the option to opt-in to the use of the OTP or retain the option of not using the OTP. Users who value a simplified authentication experience often select to opt-out of using such an OTP because the added security is not worth the delay or difficulty of waiting for, viewing, remembering, and typing in the OTP. On the other hand, the automatic outputting of the moving window of streaming stream blocks need not involve the user at all and achieves added security without any effect on the user authentication experience.

Fourth, when the server communicates the dynamic, random OTP to the user, the user must receive the OTP outside the application of interest. For example, a user logging into their bank must switch to their messaging application to view the OTP that the server provides, and then must switch back to the banking app to complete the login. On the other hand, since the automatic output of the moving window of streaming stream blocks requires no user action, the user need not leave the application of interest to have the added security of this authentication factor.

Fifth, it is possible that an outsider could convince or order the SMS telecom provider to permit the OTP to be sent to a device in addition to or instead of the authorized user. Where the OTP is sent is completely under control of the telecom provider. On the other hand, the use of streaming stream blocks places no reliance on the telecom provider to participate in the authentication event.

Sixth, to produce the next random OTP, the OTP system requires a central table or database to correlate the specified device, to be authenticated, with a seed or root cryptographic value. An outsider could compromise the stored central table and predict the next OTP for a given device. In an OTP system, only the next OTP is relevant to an authentication event, without any need to know what the value of the precedent OTPs produced prior to compromise of the central table. On the other hand, the use of streaming stream blocks means that authentication cannot be accomplished by compromise or prediction of the next stream block, but instead requires access to previous stream blocks in order to participate in the authentication event.

Authentication using streaming stream blocks achieves all of the advantages of using a random, dynamic OTP. Use of an OTP has the advantage that the next OTP to be provided cannot be predicted by outsiders, but this is also true of the moving window of streaming stream blocks. Although each stream block does have some data that stays the same over a given stream (such as the version, the account or user identifier, the device identifier, the stream identifier), each stream block also has some data that varies: the sequence number within the given stream, the time stamp, the hash of the first preceding stream block, the random number serving as the cryptographic salt, the hash of the fields of the current stream block. The content of a succeeding stream block therefore cannot be predicted. Furthermore, the likelihood of making a correct random guess for the next OTP (typically four to eight digits) is much higher than that of making a correct random guess for the much longer next stream block. In addition, some cyber-attacks have targeted seed-to-device tables stored in centralized enterprise databases that contain the cryptographic information to predict OTPs for specific devices. Authentication using streaming that originates from the device is not susceptible to such attacks.

Authentication using streaming stream blocks as a separate factor compares favorably also with authentication using a random number provided by an onboard authenticator app or an external authenticator device (also referred to as a hardware token). The onboard authenticator app, like an OTP, interrupts the user by requiting the user to access the app, view a number having several digits, memorize the number, switch back to the application of interest, and then enter the number. Similarly, a hardware token requires the user to physically obtain and view the device, study the number, and enter it into the application of interest. On the other hand, authentication with streaming stream blocks avoids the user's involvement in any of the foregoing operations and avoids the need for the user to carry a separate device. Hardware token systems have also been subjected to attacks seeking to discover a centralized seed-to-device table in order to predict OTPs generated by the hardware token.

Once the device D(x) of a user U(x) is adapted to automatically generate a stream block 2000 on a periodic or other basis for each app (x) requiring authentication and output it to chained identifier store 3000, and is adapted to automatically respond to an authentication event with authentication server 4000 by outputting the moving window of w stream blocks, then the device is configured for fully automatic operation. Here, “fully automatic operation” means only that the generation and output of a stream block takes place without user prompting or intervention and the outputting of the moving window takes place without user prompting or intervention. In a further implementation, the automatic operation is also invisible to the user.

The structural manner in which a given device D(x) is configured is now discussed.

A device D(x) has a hardware processor (defined below) and, in some example implementations, multiple hardware processors. Unless otherwise stated, the discussion below and the appended claims pertain to both the single hardware processor case and the multiple hardware processor case, using a singular “processor” for the sake of convenience. The hardware processor has a small amount of memory including registers, buffers, and cache which are used by the processor to store information for short periods of time. Such information may include instructions or data.

A hardware processor is a type of integrated circuit that contains a vast number of transistors and other electrical components interconnected so as to function as an array of logic gates in a pattern that yields predictable outputs in response to a vector of predefined machine code inputs. The hardware processor is adapted to perform a predefined set of basic operations in response to receiving a corresponding basic instruction, the corresponding basic instruction being one of a plurality of machine codes defining a predetermined native instruction set for the hardware processor. The set of predefined machine codes is finite and well-defined for each hardware processor, as are the corresponding basic operations. The set of predefined machine codes that may validly be provided as input to a given hardware processor defines the native instruction set of the hardware processor.

The machine codes of the native instruction set of a hardware processor are input to the hardware processor in binary form. In binary form, the machine codes constitute particular logical inputs that enter the pattern of logic gates that is hard-wired into (i.e., manufactured as) the hardware processor, resulting in a predictable output that depends on the particular machine code used.

Modern software is typically authored in a form other than binary and then converted through various processes such as compilation or interpretation into binary form. The machine codes must be input into a given hardware processor in binary form.

Software is often referred to as being either operating system software or applications software. In general, operating system software is thought to provide a bridge or a level of generality between the hardware of a given computer system and the application software. In general, applications software is thought to provide a bridge or a level of generality between the operating system of a given computer system and a user. Regardless, at the time software is executed, it is executed in binary form as machine codes selected from the native instruction set of the given hardware processor.

Modern software is complex, performing numerous functions and often amounting to millions of lines of source code. Each line of source code represents one or more (typically many more) individual instructions selected from the native instruction set of a hardware processor. Hardware processors have registers, buffers, cache, and the like which can store binary information. The amount of such storage is much smaller than the set of machine codes that implement a given software “program” or “app.”

The set of machine codes are therefore stored in a memory that the hardware processor can access. In other words, the memory is under control of the hardware processor. The hardware processor, when executing a particular set of machine codes selected from the native instruction set, loads the machine codes from the memory, executes the machine codes, and then loads other machine codes from the memory.

The device D(x) in some implementations has a receiver/transmitter unit having a receiver and a transmitter, with which it communicates to the outside world. The receiver/transmitter unit is under control of the hardware processor. In various implementations, the receiver/transmitter unit communicates variously through a mobile telephone network, a satellite network, a wireless local area network, a short-range wireless network such as a personal area network, a citizens' band radio network, or the like. In some implementations, the receiver/transmitter unit has no radio but connects instead through a wired medium such as a cable. In some implementations, the device has more than one receiver/transmitter unit for communication with the outside world. In the implementations discussed below, for the sake of explanation and not limitation, the communication is described as taking place over the Internet, but alternative network implementations are used in alternative implementations.

The device D(x) in some implementations has an input/output unit with which it interacts with a user. The input/output unit is under control of the hardware processor. In various implementations, the input/output unit receives inputs from, for example, a keyboard, a touch screen, a stylus, a microphone, a mouse, a motion sensor, a physical button, an embedded camera, a fingerprint sensor, or the like. In various implementations, the input/output unit provides outputs to, for example, a display, a speaker, an output port, a vibration unit, or the like.

FIG. 2 shows, in simplified schematic form, an example of any given device D(x) of any given user U(x). Although the device illustrated in FIG. 2 is a mobile phone, other implementations include a tablet, a smart watch, a smart thermostat or other household device, a smart television, a laptop computer, a desktop computer, an e-reader, a drone, an autonomous vehicle, an embedded system, or the like.

In FIG. 2, the device D(x) is indicated as having an enclosing body or case 1200. Within device D(x) is a display overlaid with a touch-sensitive membrane to form a touch screen 1210. The device possesses one or more physical user interface buttons 1220. In other implementations, the device has no physical user interface buttons. In FIG. 2 a cutaway 1250 reveals a highly simplified schematic of some internal components of the device D(x). Hardware processor 1300 communicates with and exercises control over a memory 1310, a receiver/transmitter unit 1320, and an input/output unit 1330.

FIG. 2 also illustrates the storage in memory 1310 of machine codes 1400. The machine codes 1400 are selected from the native instruction set relevant to the given hardware processor 1300. In more detail, the memory 1310 contains numerous sets of the machine codes 1400 such as a zeroth set 1400-0 selected from the native instruction set, through an n-th set 1400-n selected from the native instruction set. The zeroth set 1400-0 of the machine codes 1400 is illustrated as containing an arbitrary number of machine codes in binary format, suitable for execution on the hardware processor 1300 once loaded from the memory 1310. Likewise, the n-th set 1400-n of machine codes 1400 also contains an arbitrary number of machine codes in binary format. As used here, “arbitrary” does not mean that the codes themselves are unknown or undefined; rather, the count of how many individual machine codes in a given set varies with the functionality that the machine codes are intended to impart, and the particular count of them is not a limitative factor.

The precise implementation of the memory is performed according to the engineering needs of the given device. The memory may be implemented as a hard drive, a solid-state device, a flash memory, an external memory stick, a DRAM, or the like. Furthermore, as used herein, the term “memory” encompasses lower-level implementations where the machine codes pertain to a dedicated security processor such as in a trusted platform environment and/or are stored at a level such as described in the unified extensible firmware interface (UEFI), in a basic input-output system (BIOS), or are reflected in the makeup of a specialized integrated circuit.

To configure a device D(x) to perform authentication using streaming stream blocks, the memory 1310 is modified to include a stream block generation module comprising a first set of the machine codes (for example, a first set 1400-1 of the machine codes 1400 or the like, not separately illustrated), selected from the native instruction set, adapted to enable the processor to generate a stream block 2000 (such as the example stream block implementations described above).

Configuration of the device D(x) also includes causing the memory 1310 to include a stream block streaming module comprising a second set of the machine codes selected from the native instruction set, adapted to enable the processor to output the stream block 2000 via the receiver/transmitter unit 1320 (for storage in the chained identifier store 3000).

Configuration of the device D(x) also includes modifying the memory 1310 to include a moving window output module comprising a third set of the machine codes selected from the native instruction set, adapted to enable the processor to output the m moving window stream blocks in connection with an authentication event.

With the memory 1310 of the device D(x) thus modified, the device D(x) is adapted to perform streaming authentication using stream blocks according to the implementations mentioned above.

Additional implementations and further details of example implementations will now be discussed, first with respect to FIG. 3, which depicts in a highly simplified, schematic manner, an alternative implementation of a specific system 11 that performs streaming authentication using stream blocks.

The implementation shown in FIG. 3 embodies the concept of a customer that has an existing application such as a social media app or the like, and of a security services provider that augments the customer's system to be able to perform authentication using streaming stream blocks.

The specific system 11 includes a chained identifier store 3000 which, more specifically, is implemented using distributed ledger technology (DLT). The DLT in one implementation is blockchain. To reflect the use of DLT in the chained identifier store 3000, FIG. 3 refers to distributed ledger 3100 as a specific species of chained identifier store 3000. Distributed ledger 3100 is a specific kind of chained identifier store 3000. Distributed ledger 3100 is, in this implementation, a private, permissioned distributed ledger system. One non-limitative, concrete example of such a system suitable for use in this implementation is HYPERLEDGER FABRIC, a project of THE LINUX FOUNDATION. Other distributed ledger technology may be employed in alternative implementations. The distributed ledger 3100 has independent nodes A-F which cooperate to receive, collect, and store stream blocks such as stream block 2000 from the devices in user base 1000. The stream blocks received from the devices in user base 1000 are collected as transactions and are stored in the distributed ledger 3100 as blocks referred to herein as “chain blocks.” The chain blocks stored by distributed ledger 3100 are larger than stream blocks such as stream block 2000 and contain multiple stream blocks from multiple streams. In other words, the stream blocks are constituent elements of chain blocks. In this implementation, the chain blocks are stored as a blockchain where each chain block contains a hash of its immediate precedent (like the stream blocks where each stream block contains a hash of its immediate precedent too).

The specific system 11 includes an independent authentication server 4100 that is a species of the authentication server 4000 previously discussed. Independent authentication server 4100 is described as being “independent” since it has functions independent of those in customer application server 4600. In this implementation, the customer application server 4600 is provided by the customer and the independent authentication server 4100 is provided by the security services provider but operates within the customer's enterprise network (shown as a chained line in FIG. 3). In an example implementation, the nodes of a distributed ledger (blockchain) A-F are provided by the security services provider but hosted in part by the security services provider and in part by the customer.

D(x) indicates a representative device of a representative user U(x), as previously discussed, and now also referred to as a client. The device D(x) is already configured with machine codes 1400 selected from a predetermined native instruction set of the hardware processor 1300 (see FIG. 2) of the device D(x).

In general, at a high level, the implementation of the specific system 11 is similar to the operation of system 10 previously described but with a few additions. Prior to an authentication event, client device D(x) repeatedly generates and sends stream blocks such as stream block 2000 to the distributed ledger 3100. In particular, the client device D(x) is pre-configured to transmit its stream blocks to one or more of the nodes A-F. The nodes A-F cooperate to combine the received stream blocks (the stream blocks from the various clients) into a chain block whenever the number of received transactions reaches a threshold value or whenever a predefined passage of time has elapsed prior to the number of transactions reaching the threshold value. Each chain block is added to the copy of the blockchain maintained at each of the nodes A-F.

When the user U(x) operates device D(x) to use application (x) to access the customer application server 4600, the machine codes 1400 previously configured in the device D(x) first sends the stream blocks retained in moving window m to the independent authentication server 4100. These stream blocks may be thought of as a “stream proof.” The independent authentication server 4100 validates these stream blocks against values previously stored in the distributed ledger 3100. In particular, the independent authentication server 4100 sends a query to the distributed ledger 3100 which may be directed to one or more of the nodes A-F. When the reply from the distributed ledger 3100 indicates that the stream proof is valid, the independent authentication server 4100 requests and automatically generates an authentication token. The independent authentication server 4100 provides this temporary authentication token to the client device D(x).

After receipt of the token, and under control of the hardware processor 1300 executing the machine code 1400 configured in the memory 1310 of the device D(x), the device forwards the token, together with the user's credentials such as a username and password, or the like, to the customer application server 4600.

The customer application server uses the token as an authentication factor and uses the supplied credentials as another factor of authentication. The customer application server forwards the token for verification to the authentication server. In other implementations, factors different from or in addition to the user's credentials are used. In still other implementations, the token is used as a sole authentication factor.

Although more detail is provided below, some of the additional technical effects of authentication using stream blocks stored in a blockchain-based chained identifier store are worth noting here. These technical effects are in addition to those mentioned with respect to the system 10 previously discussed.

Since a blockchain-based chained identifier store is used to distribute and store blocks of cryptographically verifiable data in a way that records are made immutable and decentralized, authentication by validating a stream proof is performed with no central storage of security credentials, keys, passwords, or secret material. Furthermore, the use of a blockchain distributed among some or all of the nodes A-F overcomes risks associated with the compromise of any one of the nodes. For example, if a node such as node C is compromised, the insertion of false values into its ledger cannot be inserted without detection by the other nodes.

The compromise of a node, in addition, yields no information useful in predicting or generating the content of future stream blocks. Assuming the compromise of the node is detected, and it is prevented from receiving further stream blocks and chain blocks, the value of the compromised information will quickly diminish. For example, assume the moving window holds only three stream blocks, and the client sends out a new stream block every minute. The ability of the party with the compromised node, to use its already-stored stream blocks to attempt to obtain a token, passes in as quickly as one minute.

Moreover, although some users tend to use the same password for multiple accounts, and compromise of the password of a user for one app can convey access to other apps, the stream blocks differ for each different app (x) and are essentially randomized data. A theft of stream blocks of one app has no relevance to any other app and does not reveal any personally identifiable information, biometrics, cryptographic keys, passwords, or even security questions.

FIG. 4 depicts a general sequence of actions in one algorithm that effects an authentication operation in one example implementation. Compared to FIG. 3, FIG. 4 also shows a customer account registry 4700. The customer account registry 4700 stores information as to a correspondence between random numbers, generated as unique identifiers, and particular user identity, device identity, and app identity information. When used to identify any given user, such a random number is a value that uniquely represents the account for user U(x); when identifying any given device, such a random number is a value that uniquely represents the device D(x); and when identifying any given app, such a random number is a value that uniquely represents the app (x).

FIG. 4 shows numerous implementation details that are provided for the sake of providing a concrete explanation and teaching example. The precise implementation details such as function names, argument names, and the like are non-limitative.

In FIG. 4, a user U(x) attempts to access an online application (x) that requires authentication. In response to the requirement to authenticate, a client function GetToken( ) 400 is called using U(x) as an argument. The client function GetToken responds to the call by issuing an application program interface (API) call to the independent authentication server 4100 to invoke a similarly-named function GetToken of the independent authentication server 4100, supplying additional arguments such as the complete stream identifier (i.e., U(x), D(x), (x) in this example) and the stream proof (i.e., in this example, [n][n−1][n−2]). The call to the independent authentication server 4100 to obtain a token is, in this context, referred to as a token request message 405 that includes a plurality of chained identifiers. More specifically, in this implementation, the token request message 405 includes a stream identifier and the moving window of w stream blocks 2000 in connection with an authentication event.

As previously discussed, the stream proof in one implementation includes the plurality of stream blocks themselves as the chained identifiers. As also previously discussed, the stream proof in alternative implementations includes proof of possession of a plurality of stream blocks as the chained identifiers, instead of the full blocks. The teaching examples reflected in FIG. 4 and FIG. 5, and described elsewhere in relation to authentication events, are amenable to implementation of stream proof by blocks and also stream proof by proof of possession.

The independent authentication server 4100 receives the token request message 405. It thereafter generates a call to the distributed ledger 3100 API to invoke a function CheckStream( ), supplying as arguments the stream identifier and the stream proof. Here the stream proof is a plurality of stream blocks 2000 received in the token request message 405. In alternative implementations, the stream proof is a number of hashes showing proof of possession of the corresponding stream blocks. This call is more generally a verification query 410.

In this example implementation, distributed ledger 3100 receives the verification query 410 and performs a verification operation 415 with respect to the one of the respective streams that matches the stream identifier and the stream proof. In other words, the verification query includes a stream proof to be verified for one of the respective streams. The verification operation 415 in this implementation includes verifying a digital signature of each of the stream blocks and verifying whether the stream proof contains values corresponding to stored stream blocks of the particular one of the respective streams. In the implementation where the verification query 410 includes a stream proof with hashes instead of complete blocks, the verification operation 415 includes verifying whether the hashes are found in the previously stored contents, namely, in the stored stream blocks. The verification determination is therefore more generally based on whether the stream proof contains values corresponding to the stored streamblocks, whether the values are hashes or complete blocks. The distributed ledger 3100 responds to the verification query 410 with a verification determination 420 indicating whether the verification operation 415 produced an affirmative result.

When the verification determination 420 is in the affirmative, the independent authentication server 4100 generates a token 425 and transmits it to the client device D(x). The token 425, in an implementation, includes a field useful in limiting the duration of time in which the token 425 is considered valid by the system 10 or the specific system 11.

The device D(x) then prompts the user U(x) to supply a username (Uid) and password (Pwd) for the app (x). Next, the device D(x) generates a login request message 430 to the customer application server 4600 to call function Login( ) of the API of the customer application server 4600, supplying as arguments the Uid, Pwd, and token 425.

The customer application server 4600 receives the login request message 430. To validate the token 425 the customer application server 4600 accesses or sends a correspondence request message 435 to the customer account registry 4700 to obtain the value of the random number that uniquely identifies user U(x) and corresponds to the username Uid. This operation is necessary in the implementation where the independent authentication server 4100 does not contain the username Uid but does contain the random number for identifying U(x). The customer account registry 4700 responds to the correspondence request message 435 by supplying 440 the value of U(x) to the customer application server 4600. Now the customer application server 4600 has the information it needs to check the validity of the token 425 with the independent authentication se 4100.

The customer application server 4600 issues a token verification request 445 that invokes function CheckToken( ) of the independent authentication server 4100, supplying as arguments U(x) and the token 425. The independent authentication server 4100 replies with a token verification determination 450 indicating whether the token 425 is valid. This determination is based on whether a predetermined passage of time since generation of the token 425 exceeds a predetermined threshold, in one implementation. In another implementation, the determination is based on whether the user to which the token 425 was issued also matches the user U(x) indicated in the token verification request 445.

After receiving the token verification determination 450, the customer application server 4600 replies to the login request message 430 with a login determination message 455 indicating whether the login request is granted or denied. When the token verification determination 450 is in the affirmative, and when the supplied username Uid and password Pwd are accepted, the customer application server 4600 grants the login request.

FIG. 5 depicts a general sequence of actions in another algorithm that effects an authentication operation in another example implementation. This figure shows numerous implementation details that help provide a concrete explanation and teaching example but are non-limitative.

One main difference between the operations in FIG. 5, compared to the operations shown in FIG. 4, is that the authentication server dynamically shapes the stream challenge and identifies a selected subset of the moving window as the stream proof. In FIG. 4, the stream proof is the moving window. In FIG. 5, however, the stream proof includes certain stream blocks selected from the set of stream blocks that make up the moving window. In FIG. 5, the client function GetToken( ) 400 responds to being called by issuing an API call to the independent authentication server 4100 to invoke a function GetTokenChallenge( ). This message is referred to as an index indication request message 402. The independent authentication server 4100 receives the index indication request message 402 and reacts using logic that constitutes an index indication module to select one or more numbers pertaining to stream blocks. In this implementation numbers are random integer values selected from a range of values based on the size of the moving window w.

For example, assume the size of the moving window w is nine. In this instance, the moving window includes the current stream block [n] (which may be written as [n−0]), the first preceding stream block [n−1], etc. up through stream block [n−8]. The random numbers in such an implementation have values from 0 through 8. To put it more generally, a random number r is eligible for selection when r∈{0, 1, . . . , w}.

Continuing with this example, assume that the GetTokenChallenge( ) function of the independent authentication server 4100 selects three random values represented by r1, r2, and r3. In this example, the random values are r1=2, r2=6, and r3=5. The particular stream blocks of the client device moving window are selected using these random values.

The independent authentication server 4100 replies to the index indication request message 402 with an index indication message 403. The index indication message 403 includes content that indicates the random number(s) selected (in this example, the indices are 2, 6, and 5).

After receiving the index indication message 403, the client prepares a responsive token request 407 containing the stream identifier (U(x), D(x), (x)) and the stream blocks from the moving window that correspond to the indices indicated in the index indication message 403. In this example, r1=2, r2=6, and r3=5. Therefore, the responsive token request 407 is generated with a stream proof that supplies stream blocks [n−r1][n−r2][n−r3], namely stream blocks [n−2][n−6][n−5] (the second preceding stream block, the sixth preceding stream block, and the fifth preceding stream block).

Processing continues afterward in the manner already described in the context of FIG. 4.

FIG. 6 shows one registration process for a new user and a new device. In FIG. 6, machine codes 1400 must first be installed or loaded onto a device (shown as D(x)) of a client. In a registration initialization step 500, the client device generates an application level identifier (UUID). The machine codes 1400 create key pairs for use with the stream to be set up and also for use with the distributed ledger 3100. The machine codes 1400 also create a partially-filled in origin stream block OStBlk for the stream to be set up, and signs the partial origin stream block OStBlk with the stream key of the originator to produce a signed origin stream block OStBlk_s.

An initial registration message 505 is sent from the client device D(x) to the customer application server 4600. This initial registration message 505 contains, for example, the username Uid and password Pwd for the account that the user already has with the app. The customer application server 4600 verifies the Uid and Pwd from the initial registration message 505 and, if successful, sends a stream identity request message 515 to the independent authentication server 4100. The stream identity request message 515 includes, e.g., a certificate signing request (CSR) and the signed origin stream block OStBlk_s.

Upon receipt of the stream identity request message 515, the independent authentication server 4100 generates 520 a random number to uniquely identify the account U(x), avoiding the need to reference the actual Uid in the independent authentication server 4100 or in the distributed ledger 3100. As mentioned above, the customer application server 4600 accesses a customer account registry 4700 as necessary to determine how the U(x) value and the Uid correspond. At this point in the process, however, the customer application server 4600 has not yet been provided with the value of U(x). Note that, in this registration process, the Uid is not made available to the independent authentication server 4100 or the distributed ledger 3100.

After the value of U(x) is generated, the independent authentication server 4100 sends a stream initialization request message 525 to the distributed ledger 3100. In this example, the stream initialization request message 525 contains the random number generated to uniquely identify U(x), a certificate signing request CSR, and the signed origin stream block OStBlk_s.

Responsive to the stream initialization request message 525, the distributed ledger 3100 validates the signature of the OStBlk_s in a signature validation step 530. In step 535, other validations are performed. In various implementations, the validations include checking that the number of existing streams of D(x) and of U(x) does not exceed a predetermined threshold, checking that the stream identifier is unique across the distributed ledger, and/or checking that the value of U(x) does not divulge any PII.

After the other validation checks, the distributed ledger 3100 signs (step 540) the certificate signing request CSR using its private key (represented as DLId), giving a signed certificate signing request CSR. The distributed ledger 3100 also modifies (step 545) the OStBlk with its own random data to give a modified origin stream block OStBlk_m (also referred to as a complete origin stream block) for the stream. This OStBlk_m becomes the origin stream block for a new stream that pertains to the use by account U(x) of device D(x) to run application (x), in step 550. Thereafter, in step 555, the distributed ledger 3100 outputs to the independent authentication server 4100 a stream initiation message 555 with U(x), the signed certificate signing request CSR_s, and the OStBlk_m.

Now the independent authentication server 4100 can reply to the stream identity request message 515 with a stream identity response message 560 containing, e.g., the value for U(x), the signed certificate signing request CSR_s, and the OStBlk_m.

The customer application server 4600 uses its knowledge of the end user's account information such as the Uid and Pwd to update customer account registry 4700 to hold the correspondence between the Uid and the value of U(x). The customer application server 4600 also now replies to the initial registration message 505 with an initial registration response message 565.

The client device D(x) validates the signature of the OStBlk_m using the public key of the distributed ledger 3100 in step 570 and then stores the OStBlk_m and the signed certificate signing request CSR_s. After requesting (step 580) and receiving (step 585) the public configuration for the distributed ledger 3100, the machine codes 1400 start generating the stream blocks [n] etc. With each stream block, in an example implementation, the machine codes 1400, representing the logic of a streaming module in the client, invoke the function WriteToStream of the distributed ledger 3100. The streaming module is thus adapted to output a write request message 593 that includes, for example, the stream name (also referred to as the “stream identifier”) U(x), D(x), (x), the new stream block [n] signed using the private key for the stream (represented as “newStreamBlock_s”; this stream key pair was generated in step 500). The write request message 593 also includes information the distributed ledger 3100 requires for authentication, referred to hereafter as a stream challenge. In one implementation, a standing stream challenge (StreamChallenge in write request message 593 in FIG. 6) is for the device to provide the stream blocks of the moving window in their entirety. In another implementation, the device must provide only certain portions of the stream blocks, or even just the hashes of the precedent stream blocks of the moving window. The stream challenge is signed, in certain implementations, with the private key of the distributed ledger (DL) key pair generated in step 500 and the signed result is represented in FIG. 6 as “StreamChallenge_s”.

The distributed ledger 3100 responds to the write request message 593 by various validations used in example implementations including ensuring the time between the sending of the write request message 593 and its receipt at the distributed ledger 3100 is within a predetermined threshold. In step 597, the stream block [n] is committed to the blockchain by invoking a commit function. When enough new stream blocks are received from the various client devices, a new chain block is added to the distributed ledger 3100.

FIG. 7 shows an example implementation of a registration process for use when an end user U(x) has an already-registered device D(x1) registered for use with an app (x) and is streaming chained identifiers [n] to the distributed ledger 3100. To access their account from a device to be registered D(x2), a registration process similar to that shown in FIG. 6 is used in one implementation. In FIG. 7, however, the registration process for the device to be registered D(x2) takes advantage of the user's possession of the already-registered device D(x1).

In FIG. 7, an already-registered device D(x1) runs app (x). Through a user interface, the user selects a function that links a new device such as function “link new device” shown in step 600. The underlying machine codes 1400 respond by invoking a function shown in the figure, for example, as GetNewDeviceChallenge( ) in step 605. The machine codes 1400 generate a barcode from a number of values. The barcode includes data that identifies the stream identifier U(x), D(x), (x). The barcode further includes the stream challenge for already-registered device D(x1) signed with the private key of the DL key pair generated by already-registered device D(x1) and represented in step 610 as StreamChallenge_s1. This barcode is referred to as a “stream barcode”.

Through a user interface, on the device to be registered D(x2), the user selects a function to add D(x2) such as “add new device” shown in step 615. The underlying machine codes 1400 respond by opening the camera to read the stream barcode from the screen of D(x1) in step 620. The use of a barcode is an example implementation. Other ways of providing the same information from D(x1) to D(x2) are employed in other implementations.

The machine codes 1400 of the device to be registered D(x2) are given access to the raw barcode information captured by the camera of the device to be registered D(x2) through a function (shown as GetRegistrationPayload(barcode)) in step 625. In step 630 the signed stream challenge prepared by D(x1) is extracted and saved. The stream identifier U(x), D(x2), (x) is generated in step 635. A key pair for this stream is generated by D(x2) in step 640, as well as a key pair for this stream to use with the distributed ledger 3100 (a DLT key pair).

In step 645 the origin stream block [000] for the stream U(x), D(x2), (x) is generated in part and signed with the stream key generated in step 640, giving signed origin stream block OStBlk_s2.

The machine codes 1400 in the device to be registered D(x2) call a function of the independent authentication server 4100 by passing a new device pairing message 650 containing U(x), a certificate signing request CSR, the stream challenge signed by D(x1) (StreamChallenge_s1), and the partial origin block signed by D(x2) (OStBlk_s2). The independent authentication server 4100 in turn calls a function on the distributed ledger 3100 to add a new paired device with a similar new device pairing message 655.

The distributed ledger 3100 validates both the signature of D(x1) as to StreamChallenge_s1 and the signature of D(x2) as to the signed partial origin block OStBlk_s2 in step 660. Other validations are performed in various implementations in step 665 (see step 535, above, for more detail). In step 670 the certificate signing request CSR is signed using the distributed ledger's key giving CSR_s.

Processing continues in a manner similar to that already described in the context of FIG. 6 with the modification of the origin stream block to give OStBlk_m (step 675), the return of initial registration response message (step 680) to the independent authentication server 4100 and eventually to D(x2) (step 685), the validation and storage of the OStBlk_m (steps 690 and 693), and the generation of stream blocks [n] . . . , etc., in step 695. Each generated block is written to the stream U(x), D(x2), (x) via a write request message 697 like write request message 593 discussed in FIG. 6.

The operations associated with writing new stream block [n] to a stream will now be discussed in the context of FIG. 8. In general, the distributed ledger 3100 receives write request messages including information pertaining to stream blocks. The stream blocks pertain to stream identifiers and so form respective streams of the stream blocks. Each of the stream blocks (other than the origin stream blocks) is chained to an immediate precedent stream block within each of the respective streams.

In this example implementation, processing begins at step 800 where a stream block [n] such as stream block 2000 is generated. In step 810, the block is signed with the key for the given stream. The signed stream block is represented as [n]_s. The stream block [n] is saved to a secure local storage of the device D(x) in step 820 and has a status of “pending” in step 830. In step 840 a write request message is sent to the distributed ledger 3100. The message includes the identifier for the account U(x), the stream identifier U(x), D(x), (x), a signed stream challenge StreamChallenge_s, and the signed stream block to be written [n]_s.

The distributed ledger 3100 validates the signatures and the stream challenge in steps 850 and 860, and then includes the stream block [n] in stream U(x), D(x), (x) by adding it to a chain block stored in the distributed ledger 3100. Successful completion is returned in step 880, after which the status of the stream block [n] becomes “committed.”

In one alternative implementation, the entirety of the content of the new stream block [n] is not included in the write request message 840. In this implementation, the ninth field as discussed with respect to stream block 2000 is omitted since the chained identifier store 3000 can compute such a hash itself. In this implementation, the chained identifier store 3000 performs this hash computation itself for each block and stores the result locally in connection with the given block to facilitate the later processing of stream proofs.

This alternative implementation avoids the transmission of information that can be readily computed, reduces the network load, and improves security by avoiding the exposure to interception of the complete stream block.

In yet another alternative implementation, the seventh field as discussed in the context of stream block 2000, namely, the hash of the immediate precedent in the stream, is also not transmitted. The chained identifier store 3000 already has all of the stream blocks from the origin block [000] up to [n], and determines for itself the hash for the immediate precedent of any given stream block. In this implementation, unless a party, who intercepts the stream information minus the hashes, possesses the entire stream back to the origin block, that party can never correctly compute the missing hashes.

In implementations where entire streamblocks are sent from the device D(x) to the chained identifier store 3000 (or the distributed ledger 3100), the write request message is said to “include stream blocks”. In implementations in which the entire stream blocks are not transmitted, but omit either or both of the hash fields for the current or immediate precedent stream blocks, and rely on the chained identifier store 3000 (or the distributed ledger 3100) to compute the omitted hash value(s), the write request message is said to include “stream block information less one or more block hash values” or is said to be “free of one or more block hash values”. A more general way to refer to either implementation is to say that the write request message includes “stream block information” or includes “information pertaining to stream blocks”.

FIG. 9 illustrates an implementation of processing when the client D(x) is offline for a short time. In FIG. 9, the client device D(x) is shown with active memory 1310-a and secure local storage 1310-s as aspects of memory 1310 illustrated in FIG. 2.

At a given time T0, the active memory 1310-a stores newly-generated stream block [178] of a given stream U(x), D(x), (x). Stream block [178] is stored substantially simultaneously in secure local storage 1310-s. The secure local storage 1310-s stores all of the stream blocks in the moving window w. In this implementation example, the maximum size of the secure local storage 1310-s allocated for storing stream blocks [n] is enough to hold four stream blocks. At T0, the secure local storage 1310-s stores previously-generated stream blocks [175][176][177] and newly-generated stream block [178]. As explained above, stream block [178] is initially marked with a pending status, but when distributed ledger 3100 reports that the stream block has been successfully committed, the stream block [178] is also marked with a committed status indicator. In FIG. 9, each committed one of the plurality of stream blocks is shown as underlined in secure local storage 1310-s. The distributed ledger 3100 stores the entire stream of stream blocks from the origin stream block [000] through stream block [178].

By the time of T1 in this example, stream block [178] has been marked as committed and is shown as underlined in secure local storage 1310-s. At a next given time T1, the next stream block [179] is generated in the active memory 1310-a and then is stored in the secure local storage 1310-s. The limited space allocated from secure local storage 1310-s requires the deletion of stream block [175]. At this time, however, the stream block [179] is prevented by network or other effects from being sent to the distributed ledger 3100 as represented by a hollow “x”. Therefore, the distributed ledger 3100 does not yet store newly-generated stream block [179].

At a next given time T2, stream block [180] is generated in active memory 1310-a and written into secure local storage 1310-s, causing stream block [176] to be deleted locally. The temporary connection issue with memory 1310 still prevents any writes to the stream.

At time T3, as stream block [181] causes the deletion of [177] from the secure local storage 1310-s, the connection problem is resolved and all the pending blocks [179] . . . [181] are written to the distributed ledger 3100. Since the connection issue was resolved before the exhaustion of the capacity of the secure local storage 1310-s to store pending streamblocks, no stream blocks were lost.

At time T4, the connection with distributed ledger 3100 goes out again, and progress continues at time T5 as with T2, and again at time T6.

At time T7, however, the generation of stream block [185] would result in the exhaustion of the capacity of secure local storage 1310-s to store pending blocks. To maintain the integrity of the stream so that each stream block is linked to its predecessor, the stream block [185] is generated so as to contain the hash of stream block [181] as its immediately preceding stream block. Stream blocks [182]-[184] (i.e., the ones of the plurality of stream blocks in the moving window lacking the committed status indicator) are dropped by a deletion operation and never sent to distributed ledger 3100. Their absence makes room for more stream blocks, and so at times T8 and T9 new pending stream blocks [186] and [187] are respectively generated. At time T9, the connection with distributed ledger 3100 is working and so stream blocks [185]-[187] take their place in the chain after stream block [181].

To review, the secure local storage 1310-s stores stream blocks, making room as needed to accommodate new stream blocks but always retaining at least one committed stream block. Once a threshold indicates that further storage of another stream block cannot be accommodated without deleting the most-recently committed stream block (for example, in response to a communication status with the chained identifier store), the pending stream blocks are purged, and newly-generated stream blocks are chained to the most-recently committed stream block.

The following is an example application programming interface (API) interface (API). The API is provided as a teaching example of how a concrete implementation of the algorithms described above could be approached.

Table 1 below provides sample data structures that relate to the sample algorithms in Tables 2 through 9. These tables include statements that resemble a high-level programming language. Those familiar with this field will understand how to vary the numerous specific details of this teaching example to develop machine codes appropriate to the hardware processor of their computing system, server, and/or device.

TABLE 1 API structure definitions package blocks const ( // StreamBlockVersion is the current supported / implemented StreamBlock struct version. StreamBlockVersion uint32 = <version> // StreamBlockLengthBytes is the length [in bytes] of a StreamBlockStruct data struct. StreamBlockLengthBytes = <int> // StreamIDLengthBytes is the length [in bytes] of the StreamID. StreamIDLengthBytes = <int> // StreamBlockSignatureLength is the length [in bytes] of the cryptographic signature StreamBlockSignatureLength = <int> // StreamBlockSaltLength is the length [in bytes] of the fresh salt of a block StreamBlockSaltLength = <int> // StreamBlockHashLength is the length [in bytes] of the SHA3-256 hash of a block StreamBlockHashLength = <int> // StreamBlockBodyLengthBytes is the length [in bytes] of just the hashed and signed material; // that is to say, the block body sans BlockHash and Signature StreamBlockBodyLengthBytes = StreamBlockLengthBytes − (StreamBlockHashLength + StreamBlockSignatureLength) ) const ( // MaxStreamBlockChainLength is the maximum number of blocks that may be either stored // locally at a client or transmitted by a client to Fabric. // The StreamBlockChain needs to be limited in size in order to not exceed reasonable limits of // secure storage or transmission MaxStreamBlockChainLength = <int> // StreamChallengeLength is number of stream blocks that need to be sent as proof that an identity // is authorized to perform an action with that stream, i.e. extend the stream or // login using the stream StreamChallengeLength = <int> ) /* StreamBlockChain is the struct representing the array of blocks */ type StreamBlockChain struct { Version uint32 Blocks [MaxStreamBlockChainLength]StreamBlock } /* StreamBlock is the struct representing the concrete stream block within Chaincode, it currently represents the version “1” block. */ type StreamBlock struct { Version uint32 SequenceNum uint32 Time int64 AccountID [16]byte DeviceID [16]byte StreamID [StreamIDLengthBytes]byte PrevBlockHash [32]byte Salt [StreamBlockSaltLength]byte BlockHash [StreamBlockHashLength]byte Signature [StreamBlockSignatureLength]byte }

ConstructOriginStreamBlock generates and returns an origin hash block. At this stage, the client only partially fills in the fields of the originHashBlock, submits it upon a Registration request. Upon successful registration, it receives back a fully filled in and signed originStreamBlock that then begins the root of its stream chain. The block is signed by the privateKey that is passed is as privateKeyBytes.

TABLE 2 ConstructOriginStreamBlock func ConstructOriginStreamBlock(deviceID string, streamID [ ]byte, streamPrivateKeyBytes [ ]byte) (originStreamBlock StreamBlock, err error) { //DeviceID as bytes deviceIDAsBytes, _ := uuid.Parse(deviceID) // Check length of streamID. This is the public key if len(streamID)!= streamIDLengthBytes { return StreamBlock{ }, error( ) } streamBlock := StreamBlock{ Version: StreamBlockVersion, SequenceNum: 0, Time: <currentTime>, DeviceID: deviceIDAsBytes. StreamID: streamID, } // Compute the hash the StreamBlock hash, _ := streamBlock.HashStreamBlock( ) streamBlock.BlockHash = hash // Sign the stream block signature, _:= streamBlock.Sign(streamPrivateKeyBytes) streamBlock.Signature = signature return StreamBlock, nil }

ConstructNextStreamBlock takes a stream block and generates the next one is sequence. This means that it increments the sequenceNum, sets newBlock.PrevBlockHash=block.BlockHash, sets a new salt, hashes, and signs the block.

TABLE 3 ConstructNextStreamBlock func ConstructNextStreamBlock(block StreamBlock, streamPrivateKeyBytes [ ]byte) (newStreamBlock StreamBlock, err error) { newBlock := StreamBlock{ Version: StreamBlockVersion, SequenceNum: block.SequenceNum + 1, Time: <currentTime> AccountID: block.AccountID, DeviceID: block.DeviceID, StreamID: block.StreamID, } // Set the prevHash of the block to the hash of the previous stream block newBlock.PrevBlockHash, _ = block.HashStreamBlock( ) // Set the Salt of the newBlock // Generate a fresh salt newBlock.Salt, _ := GetRandomBytes(StreamBlockSaltLength) // Compute the hash the streamBlock hash, err := newBlock.HashStreamBlock( ) newBlock.BlockHash = hash // Sign the stream block signature, _ := newBlock.Sign(streamPrivateKeyBytes) newBlock.Signature := signature return newBlock, nil }

Sign is a StreamBlock method that signs a block, adds the signature string to the block.

TABLE 4 Sign func (block StreamBlock) Sign(privateKeyBytes [ ]byte) (signature [ ]byte, err error) { // Hash the streamBlock. This will generate a hash of all fields in the stream block // except for hash itself and signature hash, _ := block.HashStreamBlock( ) // Sign the stream block using its hash as input signature, _ = Sign(hash, privateKeyBytes) return signature, nil }

VerifyAsOriginBlock is a special case of verifyBlock that verifies an origin block cryptographic signature according to our rules for origin blocks. Because these blocks do not have a chain (they are the root), they are only partially complete blocks and therefore special cases of the verification process.

TABLE 5 VerifyAsOriginBlock func (block StreamBlock) VerifyAsOriginBlock( ) (bool, error) { // Block can't be an origin block if block.SequenceNum!= 0 { return false, nil } modifiedBlock := block /* Zero the fields the clients didn't know at origin signing time */ modifiedBlock.AccountID = [16]byte{ } modifiedBlock.PrevBlockHash = [32]byte{ } modifiedBlock.Salt = [32]byte{ } tryHash, _ := modifiedBlock.HashStreamBlock( ) if!CompareHashes(tryHash, block.BlockHash) { // Expected hash and declared (in-block) hash do not match return false, nil } return CheckSignature(tryHash, block.Signature, block.StreamID) }

VerifyBlock verifies that a StreamBlock is a proper, well-formed and cryptographically correct block to extend the chain represented by ‘history’. The parameter ‘history’ represents the full chain history. If it is empty, only ‘block’ is verified to be cryptographically self-consistent, regardless of the value of ‘shallow’ NOTE: ‘history’ is expected to be ordered with oldest-first (index 0). The parameter ‘shallow’ determines whether the entire chain should be checked, or just the previous block in the chain. To be clear: With ‘shallow=true’ ‘block’ is verified against ‘history[len(history)-1]’ only, while with ‘shallow=false’ the entire chain is checked.

TABLE 6 VerifyBlock func (block StreamBlock) VerifyBlock(history [ ]StreamBlock) (bool, error) { if history == nil || len(history) == 0 { return false, error( ) } // NOTE: history should be oldest-first/most-recent-last lastBlock := history[len(history)−1] if block.Version!= lastBlock.Version { return false, error( ) } if block.AccountID!= lastBlock.AccountID { return false, error( ) } if block.DeviceID!= lastBlock.DeviceID { return false, error( ) } if block.StreamID! = lastBlock.StreamID { return false, error( ) } // Can't add a block that is older than latest if block.Time < lastBlock.Time { return false, error( ) } // Sequence number must be latest + 1 if block.SequenceNum!= (lastBlock.SequenceNum + 1) { return false, error( ) } // Make sure Salt is not trivial/zero-byte data emptyByteVar := [32]byte{ } if block.Salt == emptyByteVar { return false, error( ) } // Make sure BlockHash is... actually the hash of the block actualHash, err := block.HashStreamBlock( ) if err!= nil { return false, error( ) } if!CompareHashes(actualHash, block.BlockHash) { return false, error( ) } signatureOk, _ := CheckSignature(block.BlockHash, block.Signature, block.StreamID) if!signatureOk { return false, error( ) } computedPrevBlockHash, _ := lastBlock.HashStreamBlock( ) if!CompareHashes(computedPrevBlockHash, block.PrevBlockHash) { return false, error( ) } return true, nil }

HashStreamBlock is a helper function to hash a stream block. This will hash all of the fields of the StreamBlock minus BlockHash and Signature, which are not used in hashing

TABLE 7 HashStreamBlock func (block StreamBlock) HashStreamBlock( ) ([32]byte, error) { // Serialize streamBlock to bytes hash := sha3.Sum256(block.ToBytes( )) return hash, nil }

MakeStreamChallenge is a simple challenge variation that creates the stream challenge for a given stream history.

TABLE 8 MakeStreamChallenge func MakeStreamChallenge(history [ ]StreamBlock) ([32]byte, error) { // To hash the stream history, simply concatenate them as a contiguous // stream of bytes which will be our hash input var concatBlockBuffer bytes.Buffer for block in range history { // Serialize each block to a byte representation blockBytes := block.ToBytes( ) // Append the hash-able part of the block to our concat buffer lenWritten, err := concatBlockBuffer.Write(blockBytes[0:StreamBlockBodyLengthBytes]) } // Now that we have concatenated all of the hash-able parts of our blocks together in a contiguous buffer, we hash it hash := sha3.Sum256(concatBlockBuffer.Bytes( )) return hash, nil }

CheckStreatnChallenge compares supplied hash+signature strea.mChallengeSigned) of last N many blocks against given blocks in the ledger (lastNBlocks)

TABLE 9 CheckStreamChallenge func CheckStreamChallenge(corshaAccountID, streamID, streamChallengeSigned string, lastNBlocks [ ]Stream Block) (bool, error) { if len(corshaAccountID) == 0 { return false, error( ) } if len(streamIDBase64) == 0 { return false, error( ) } if len(streamChallengeSigned) == 0 { return false, error( ) } // Currently requiring either 1 block for history or StreamChallengeLength // number of blocks. If checkStreamChallenge is called from primeStream then // lastNBlocks must have just one block (originStreamBlock). // All other calls to checkStreamChallenge after primeStream can // expect to have the minimum number of challenge blocks in the history N := len(lastNBlocks) if N!= 1 && N!= StreamChallengeLength { return false, error( ) } // Get hash and signature bytes hash := streamChallenge.Hash signature := streamChallenge.Signature // Verify signature signatureOk, err := CheckSignature(hash, signature, streamID) if!signatureOk { return false, error( ) } // Check that pub key is the same as the one used in our actual block/stream history? // NOTE: we ensured len(streamBlocks) > 0 at the start of this func if lastNBlocks[0].StreamID!= streamIDArray { // This would be a sign of someone trying to abuse chaincode args return false, error( ) } ourHash, err := MakeStreamChallenge(lastNBlocks) if!CompareHashes(ourHash, hash) { return false, error( ) } // At this point: // - The supplied challenge was properly signed, // - The streamID/pub key used in signing matches the streamID already in the ledger // - The supplied hash matches what we get when we hash the last N blocks from the ledger // for the given stream. // So challenge accepted return true, nil }

AppendBlock appends a new block to the given StreamBlockChain. If StreamBlockChain is already full, an item will be deleted from the front. Note: The proposed block will be verified to make sure it is good to add to this chain

TABLE 10 AppendBlock func (stream StreamBlockChain) AppendBlock(proposedBlock StreamBlock) error { success, err := proposedBlock.VerifyBlock(stream.Blocks, true) if!success { return error( ) } len := stream.Length( ) if len == MaxStreamBlockChainLength { // Our stream chain is full and we need to pop one off the front in order to add // this new proposed block stream.Blocks.popHead( ) len-- } stream.Blocks[len] = proposedBlock return nil }

The foregoing API is not intended to provide a complete solution, but just an implementation example for the algorithms described earlier. Further functions are necessary to provide a complete solution.

One further function involves logout by the user. In an example implementation, the customer application server 4600 handles this through session management.

Yet another further function involves handling a user's deletion of a particular stream U(x), D(x), (x) from a device. When an account within an app has been deleted from a device, the stream is frozen at the distributed ledger 3100 so that no further writes or login attempts may be made using that stream. Upon detection that a stream has been deleted from a device, a call is placed from the device to the independent authentication server 4100. The call identifies the user's account U(x) and the stream U(x), D(x), (x), and includes a stream challenge signed by the client. The independent authentication server 4100 deletes any pending tokens for U(x), and then the independent authentication server 4100 calls a function of the distributed ledger 3100 to delete the stream.

The distributed ledger 3100 validates the request, revokes the authority of any identifiers associated with the stream, and then marks the stream as frozen.

Another further function for a complete implementation involves deregistering the entire account for a user. When an account is deregistered, its associated streams must all be frozen. Deletion of the streams is an option, but freezing the streams permits a full audit history. In the context of the above examples, the customer application server 4600 sends the independent authentication server 4100 an instruction to deregister the entire account of user U(x). When deregistering an account, the independent authentication server 4100 deletes any pending login tokens for the U(x). The independent authentication server 4100 then calls the distributed ledger 3100 to mark all streams associated with U(x) as frozen and revokes the authority of any identifiers associated with the U(x).

In one implementation, communications between the client device D(x), the independent authentication server 4100, and the distributed ledger 3100 are all implemented using mutual TLS.

The multiple concrete implementations above are provided so the reader already familiar with this technology is taught how to obtain the benefits of enhanced security.

The implementations discussed above also have the beneficial effect of increased efficiency for users, reducing the operations that users are forced to undertake and reducing the time users must spend in completing authentication operations.

Moreover, the increased efficiency also is realized in the internal functioning of the devices themselves, including the client device D(x), the independent authentication server 4100, the customer application server 4600, and the distributed ledger 3100. For example, by streaming the chained identifiers in the background, a client device has fewer operations to perform at the time of an authentication event when compared with OTP or other multifactor systems.

Other API features and other functions will occur to those familiar with this technology, and such variations are to be expected in the light of the complete and detailed teaching examples provided above. Such variations, however, should not be considered outside the scope and spirit of the claims below 

There is claimed:
 1. An apparatus, intended for use in an authentication event, comprising: a hardware processor that performs a predetermined set of basic operations in response to receiving a corresponding basic instruction, the corresponding basic instruction being one of a plurality of machine codes defining a predetermined native instruction set for the hardware processor; a memory under control of the hardware processor; a transceiver under control of the hardware processor; a stream block generation module comprising a first set of the plurality of machine codes that enables the hardware processor to generate and store a plurality of stream blocks, including at least a current stream block and a first preceding stream block thereof, the current stream block including a hash of the first preceding stream block, each stream block of the plurality of stream blocks having a respective content; a streaming module comprising a second set of the plurality of machine codes that enables the hardware processor to control the transceiver to output the current stream block; a moving window module comprising a third set of the plurality of machine codes that enables the hardware processor to: store a moving window of the plurality of stream blocks; and control the transceiver to output a stream proof that includes a proof of possession of at least one of the plurality of stream blocks, and that is based on the respective content of at least one of the stream blocks of the moving window; and the memory being configured with the first set of the plurality of machine codes, the second set of the plurality of machine codes, and the third set of the plurality of machine codes.
 2. The apparatus of claim 1, wherein the stream proof is based on the respective content of at least the current stream block and the first preceding stream block.
 3. The apparatus of claim 1, wherein the stream proof is based on the respective content of all of the stream blocks of the moving window.
 4. The apparatus of claim 1, wherein the stream proof is based on the respective content of a selected subset of the stream blocks of the moving window.
 5. The apparatus of claim 4, further comprising: an index indication module comprising a fourth set of the plurality of machine codes adapted to enable the hardware processor to select the selected subset of the plurality of stream blocks based on an index indication message received via the transceiver; and the memory being further configured with the fourth set of the plurality of machine codes.
 6. The apparatus of claim 1, further comprising the streaming module being adapted to output the current stream block in a write request message to a chained identifier store.
 7. The apparatus of claim 6, wherein the write request message is adapted to invoke a commit function of a distributed ledger.
 8. The apparatus of claim 7, wherein the distributed ledger is a blockchain.
 9. The apparatus of claim 6, further comprising: the moving window module maintaining, for each committed one of the plurality of the stream blocks in the moving window, a committed status indicator; the moving window module being adapted to perform a deletion operation for ones of the plurality of the stream blocks in the moving window lacking the committed status indicator; and the moving window module being further adapted to perform the deletion operation based on a communication status with the chained identifier store.
 10. An authentication server method, comprising: receiving a token request message having a stream identifier and a stream proof, wherein: the stream identifier indicates a device that generated a stream of stream blocks and corresponds to the stream; the stream of the stream blocks includes at least a current stream block, a first preceding stream block, and a respective origin stream block; the current stream block includes a hash of the first preceding stream block; each of the stream blocks of the stream has a respective content; and the stream proof is based on the respective content of at least one of the stream blocks; generating a verification query having the stream identifier and the stream proof, communicating the verification query to a chained identifier store; receiving a verification determination pertaining to the verification query; and if the verification determination is affirmative, generating a token pertaining to the stream identifier and communicating the token in a response to the token request message.
 11. The method as in claim 10, wherein the stream identifier further indicates a user of the device.
 12. The method as in claim 10, wherein the stream proof comprises a proof of possession of a plurality of the stream blocks.
 13. The method of claim 10, further comprising: receiving an index indication request message; generating a set of random values corresponding to particular stream blocks of a client device moving window; generating an index indication message containing the set of random values; and communicating the index indication message in a response to the index indication request message.
 14. The method of claim 10, further comprising: receiving a stream identity request message including a partial origin stream block; generating an account identifier to uniquely identify an account for an originator of the partial origin stream block; generating a stream initialization request message including the partial origin stream block; communicating the stream initialization request message to the chained identifier store; receiving from the chained identifier store a stream initiation message; obtaining from the stream initiation message a complete origin stream block, based on the partial origin stream block, defining the respective origin stream block for the stream; generating a stream identity response message including the complete origin stream block and the account identifier; and responding to the stream identity request message with the stream identity response message.
 15. A method for distributed ledger operation, comprising: receiving a write request message including a new stream block to be added to a stream of committed stream blocks, a stream identifier, and authentication information, wherein: the committed stream blocks of the stream include at least a current stream block, a first preceding stream block, and a respective origin stream block, the stream identifier corresponds to a device that generated the committed stream blocks, and the authentication information includes a stream challenge to prove possession of one or more of the committed stream blocks; performing a validation of the stream challenge to determine whether the stream challenge proves the possession of the one or more of the committed stream blocks; when the validation proves the possession of the one or more of the committed stream blocks, storing and committing the new stream block as one of the committed stream blocks of the stream; receiving a verification query including a stream proof to be verified for the stream; making a verification determination based on whether the stream proof contains values from the committed stream blocks; and responding to the verification query based on the verification determination.
 16. The method of claim 15, further comprising storing the stream blocks as constituent elements of one or more chain blocks, wherein the chain blocks are stored as a blockchain.
 17. The method of claim 15, wherein the stream challenge in the write request message includes stream block information less one or more block hash values.
 18. The method of claim 15, wherein the current stream block is chained to the first preceding stream block by containing a hash of the first preceding stream block.
 19. The method of claim 15, wherein: the stream identifier further corresponds to a user of the device that generated the committed stream blocks; and the stream identifier is free of personally identifiable information.
 20. The method of claim 15, wherein the stream identifier further corresponds to an app of the device that generated the committed stream blocks. 